As a magnetic recording/reproducing apparatus, the best known is a hard disk drive (HDD). As to a magnetic head to be used for the HDD, perpendicular recording method has become a predominant recording method in order to improve recording density with respect to a hard disk. The perpendicular recording method provides not only a high linear recording density but also an advantage that the recording medium after recording is less influenced by thermal fluctuation. A magnetic head for perpendicular recording is disclosed, for example, in U.S. Pat. No. 6,954,340.
On the other hand, recently, the importance of data backup for data erasure problem has increased with increase in volume of data to be stored in an information processing device such as a server. As a device for backing up large-volume data, there has been widely used a magnetic tape device (magnetic recording/reproducing apparatus) typified by an LTO (Liner Tape-Open). In the case of the LTO, as much as 1.6 Tbytes data can be recorded on a half-inch width magnetic tape at a transmission rate of 120 Mbytes/sec or more.
The magnetic tape device is provided with a magnetic head for recording data on a magnetic tape or reading data recorded on the magnetic tape. The magnetic head is of the linear recording type, wherein since data is to be recorded and reproduced at every track defined along a longitudinal direction of the magnetic tape, a plurality of recording and reproducing elements for each track are arranged at intervals along a magnetic tape width direction. Typically, the magnetic head has recording and reproducing elements for 16 channels. Such a magnetic tape device is disclosed, for example, in Japanese Unexamined Utility-Model Application Publication No. 5-73728.
In both the magnetic head to be used for an HDD and the magnetic head to be used for an LTO, the recording element includes a first magnetic film, a second magnetic film, a coil film, and a coil insulating film. The first magnetic film has a first pole portion, and the second magnetic film has a second pole portion opposed to the first pole portion with a magnetic gap film therebetween and is joined to the first magnetic film at a back gap portion that is located in a rearward position with respect to a medium facing surface. The coil film extends around the back gap portion. The coil insulating film is typically made of an organic insulating resin and encloses the coil film. The second magnetic film is formed over the coil insulating film, covering an area extending from the medium facing surface to the back gap portion, i.e., a portion corresponding to the front half of the coil turn. The second magnetic film does not lie on the rear half of the coil turn.
As means for forming the second magnetic film, there are two methods. The first method is a frame plating method, while the second method is a sputter deposition method. In the case of the frame plating method, at first, after a plating undercoat film is formed on the surface of the coil insulating film and its surrounding area by sputtering or the like, a resist frame corresponding to a pattern of the second magnetic film is formed on the plating undercoat film, and a plated film is grown on the plating undercoat film within an area defined by the resist frame, thereby forming the second magnetic film of a given pattern.
Thereafter, the resist frame is removed, and then an unnecessary plating undercoat film is removed by dry etching. Since the unnecessary plating undercoat film is exposed at the rear half of the coil insulating film, on which the second magnetic film does not exist, dry etching is also performed on the rear half of the coil insulating film.
In the case of the sputter deposition method being the second method, after a magnetic film is formed by sputtering, the second magnetic film is obtained such that the magnetic film is etched into a given pattern by dry etching. The magnetic film formed by sputtering has excellent abrasion resistance as compared with the plated film. This advantage is particularly desirable for a magnetic recording/reproducing apparatus typified by an LTO (Liner Tape-Open). Since the sputtered film for the second magnetic film is formed on the surface of the coil insulating film, dry etching is also performed on the rear half of the coil insulating film.
Regardless of which one of the first and second methods is adopted, as described above, dry etching is performed on the rear half of the coil insulating film in the course of formation of the second magnetic film. Therefore, if the thickness of the coil insulating film is insufficient, the coil film lying inside the coil insulating film will be exposed to etching. Avoiding this problem requires an increase in thickness of the coil insulating film, which increases the distance between the second magnetic film to be formed on the surface of the coil insulating film and the coil film, deteriorating the electromagnetic characteristic.